In Phase I, genes coding for Epstein Barr Virus (EBV) nuclear antigen (EBNA-1) and diffuse early antigen (EA-D) were expressed in bacteria and used to construct sensitive enzyme linked immunosorbent assays (ELISA) for human serum IgG levels against these antigens. The assays were diagnostic for monoucleosis and nasopharyngeal carcinoma and prognostic for the course of the diseases. The Phase II studies will significantly advance the Phase I studies in three ways: (1) Additional assays will be developed to measure antibody to EBV viral capsid antigen (VCA) and restricted early antigen (EA-R). (2) The labor intensive protocols of Phase I will be simplified and made acceptable to clinical laboratories. (3) The assays will be designed to measure IgM, IgA, and IgG3 classes of antibody in addition to IgG. The first goal of Phase II is to express EBV viral capsid antigen(s) VCA and restricted early antigen (EA-R) in bacteria and to generate ELISA to measure human immune response to these antigens. The second goal is to create prototype commercial 96- well EBV-ELISA Kits having the capability of measuring classes of antibody to specific EBV antigens. The third goal is to use the EBV-ELISA kits to obtain data on serum samples which have been well characterized by immunofluorescence assays and previous ELISA studies. The fourth goal is to compare the EBV-ELISA kits with commercial heterophile and immunofluorescent assays in collaboration with clinical laboratories.